Search

With the growing demand for fuel and simultaneous pollution caused by the use of traditional fuel sources, the quest for clean energy source is the biggest challenge forward. Thus, has given way to...

Ternary alloys of general composition (TiFe)100-xMx (M = Co, Nb) have been synthesized from pure metals through high-energy ball milling. The maximum concentration of alloying components allowing formation of single phase TiFe-type compounds has been defined as 2 at.%. The hydrogenation behavior of the mechanical alloys in comparison with the arc-melted ones of the same composition has been studied by a combination of volumetric and calorimetric techniques. Influence of the alloy composition and the synthesis mode on the crystal structure of TiFe and its hydrides has been evaluated. It has been shown that the thermochemical method based on calorimetric titration provides more accurate information about phase transformations in the nanocrystalline metal hydride systems. The obtained results show that the third components slightly affect the hydrogen storage performance of non-equilibrium mechanical alloys in contrast with alloys produced by conventional melting.

Mechanical plating deposits coatings by cold welding fine particles to a workpiece through ball or shot impact treatment, for example in ball mills. This process offers flexibility in selecting material systems because the formation of coatings occurs in the solid state at near room temperature and ambient pressure. However, parametric optimization of the process remains a challenge since many parameters affect the process efficiency. The goal of this study was to numerically investigate the behavior of the balls and a substrate sample in a planetary ball mill and thus to elucidate the mechanisms involved in this mechanical plating treatment. An aluminum substrate with aluminum‑carbon nanotube coating system that was previously investigated experimentally was simulated. A discrete element method model was proposed to perform numerical simulations to predict the energy, frequency, and angle of ball-to-substrate collisions. Measurements were also conducted to determine the friction coefficient necessary for the simulation. The results revealed that small balls caused more frequent and mild collisions with the substrate predominantly in the tangential direction. These collisions are assumed to be the primary contributor to the coating formation. Collisions between large balls and the substrate were less frequent but had greater intensity, and the probability of tangential and normal collisions was approximately equal. The numerical results were qualitatively supported by the as-treated substrate roughness measurements determined in this study.

In the present work, a new preparation method for metal-polymer composite materials for hydrogen separation which consist of hydride-forming intermetallic compound LaNi5 and polyethylene was developed. According to this technique, the mechanical activation of the initial powder mixtures was employed to provide good interface between the phases. A series of composite membranes with various filler concentrations was synthesized and characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. The gas transport properties of the obtained materials in relation to H2, O2, N2, CO2 and CH4 were tested. The results indicate that the addition of the hydride-forming intermetallic compound to the barrier polymer leads to significantly improved selectivity with respect to hydrogen. The proposed method can be considered as a promising approach to producing of high performance composite membranes for hydrogen separation.

The background temperature of milling bodies and processed material is analyzed using calorimetric measures and methods of melting of reference substances during mechanical alloying of powders in planetary ball mill. It is shown that estimation of the background temperature using the calorimetric method provides more precise measurements compared to the melting method of reference substances. The dependence of background temperature change on mechanical alloying time, vial filling coefficient, mixture content of processed materials, rotation velocity of carrier, and processing atmosphere is presented.

Ti-based alloys containing Pd, Au, and Nb were produced by tilt-casting and subsequently dual-axially forged at elevated temperatures. It is shown that the mechanical properties, electrochemical behavior and biocompatibility of the studied alloys are close to, or even better, than those of typical commercial Ti-based low-alloys widely used as biological implants. This demonstrates that the Ti94Pd3Au3, Ti94Pd3Nb3 and Ti94Pd6 alloys showed a good potential for application as biomaterials.

Ti-Al intermetallic coatings thickness of about 60–150 μm was fabricated on Al, Ti, and hypo-eutectoid steel substrates by mechanical alloying (MA) using a vibratory ball mill. The coatings was then laser treated to obtain homogenous and equilibrium structure. Phase composition and the cross-sectional microstructure of the coatings were investigated using X-ray diffraction and the Scanning electron microscopy respectively while chemical analysis of the coatings was carried out using Bruker energy-dispersive X-ray Spectrometer (EDS). Micro-hardness (HV) of the obtained coatings was observed to be increased more than twice after the deposition and subsequent laser treatment in comparison with microhardness of the initial substrates materials.. Surface roughness of the obtained coatings was also reduced significantly after laser treatment i.e. for Al substrate it reduced from 52 μm to 26 μm. The parameters of mechanical alloying and laser treatment used in this work provided a successful way to deposit nano-structured intermetallic coatings with homogenous and smooth surface finish and high value of micro-hardness.

Bulk composites based on Cu 54 Pd 28 P 18 metallic glass and polytetrafluoroethylene (PTFE of about 1 mass %) were produced by mechanical alloying method with subsequent spark plasma sintering. The spark plasma sintering was done at the temperature close to the super cooled liquid region of the metallic glass. Structure and thermal properties of the obtained metallic glass/polymeric composite samples were investigated. It was found that composite sample (Cu 54 Pd 28 P 18 /PTFE) has a relatively high thermal conductivity but the appearance of the crystalline phases including oxide phase (Cu 2 O) on the border between the metallic glass particles, affected the physical properties badly. The obtained results can be beneficial in terms of obtaining different antifriction composite materials based on metallic glass and self-lubricated polymers.

Al/CNT coatings were deposited on Al substrates by a ball impact treatment method using balls of 3, 4 and 8 mm in diameter and treatment time of 1–4 h under ambient pressure and air atmosphere conditions. The morphology and structure of fabricated coatings were investigated by scanning and transmission electron microscopy. Also, the obtained coatings were characterized for microhardness and wear resistance. The results revealed that smaller balls yield better characteristics of coatings as compared with larger balls. The best condition was found to be 3-mm grinding ball and 3-h treatment. It was found that the thickness of hardened layer is about 150 μm for all treatment conditions examined. The Al/CNT coated samples demonstrated a better tribological behavior in comparison with the uncoated Al substrate.

Ti-based alloys containing Fe, Au, and Nb were produced by a tilt-casting method, subjected to a subsequent dual-axially forging operation, with their properties being studied. The research evidenced that though Ti 94 Fe 3 Au 3 and Ti 94 Fe 3 Nb 3 alloys had relatively high biocompatibility, they were very brittle during tensile tests. The dual-axially forged Ti 94 Au 3 Nb 3 alloy exhibited relatively good tensile mechanical properties (tensile strength up to 740 MPa, elongation of ∼13% and elastic module of ∼85 MPa). The average value of the hemolysis of the Ti 94 Au 3 Nb 3 alloy was found to be around 0.01896%. The Ti 94 Au 3 Nb 3 alloy showed a good potential to be applied as a biomaterial.

The most common hydrogen storage alloys (TiFe, Mg 2 Ni and LaNi 5 ) were chosen for studying the effect of high energy ball milling (HEBM) on the ability of intermetallic powders to form bulk compact samples (pellets) by solid-state bonding without binder. The role of internal energy accumulated in the material during activation treatment on formation of contact surfaces between the particles was considered. It was shown that the consolidation of the intermetallic hydrogen storage alloys prepared by HEBM allows obtaining porous bulk nanostructured samples which demonstrate simplified hydrogen activation procedure, higher thermal diffusivity and good durability after multiple absorption-desorption cycles.

The electrochemical behavior and biocompatibility of the micro/nano-structured α+β Ti–3.5Fe–3.9Cu alloy were investigated in this work. The alloy was produced by tilt-casting method and subjected to subsequent hot dual-axial forging at 1173 K. It is shown that the electrochemical behavior and biocompatibility of the Ti–3.5Fe–3.9Cu alloy are close to, or even better, than those of a typical commercial Ti-6Al-4V alloy widely used as implants. This demonstrates that the Ti–3.5Fe–3.9Cu alloy shows a good potential for application as biomaterial.

Uniaxial compression is used to apply cyclic loading within the elastic range to samples of Zr 61 Cu 27 Fe 2 Al 10 bulk metallic glass (BMG). The results are twofold. On one hand the microhardness measured on the end-faces of the samples shows an increase of ∼8% together with a slight gradual increase in the Young's modulus after the 2nd cycle. This appears similar to hardening induced by elastic cycling in nanoindentation. The microhardness measured in the centre of the sample or on the side faces of the BMG samples show little or no change as a result of cyclic loading. These results suggest that the apparent hardening of the end-faces is a surface effect attributed, not to relaxation, but to a build-up of anelastic strain, associated with local anisotropy and stresses arising from uneven loading of the samples. This is confirmed by the decay of the apparent hardening after a several days of natural ageing at room temperature. On the other hand an effect similar to structure rejuvenation takes place in the central part of the samples leading to higher specific heat capacity of the cycled samples, larger crystallization and relaxation enthalpies.

In this research, the mechanism of mechanical alloying (MA) synthesis of TiFe intermetallic compound (IMC) from individual components Ti and Fe has been studied. The partition coefficient of the apparent diffusion and the reaction rate constant during MA solid-state synthesis of the TiFe intermetallic compound in a planetary ball mill have been estimated. The results indicate that the apparent diffusion coefficient is close to 10 –11 cm 2 /s that is approximately one order higher than the conventional high temperature diffusion coefficient. The reaction rate constant is close to 1.75·10 −6 . The relation between the structure and the hydrogen storage properties of MA synthesized IMC TiFe have been briefly discussed.

In our research we obtained composites based on high-density polyethylene (HDPE) reinforced with Mg67,5Ca5Zn27,5 metallic glass by co-extrusion and compression. The co-extrusion and compression procedures have been provided at temperatures of supercooled liquid temperature region of both materials (between the glass transition temperatures (Tg) and crystallization temperature (Tx)). We investigated the mechanical properties and performed the structure characterization of the obtained polymeric/metallic glass composite samples. A positive effect of triethoxyvinylsilane on the adhesion between polymeric matrix and metallic glass reinforced particles was discovered. It was also found that composite samples (HDPE/Mg67,5Ca5Zn27,5) had excellent adhesion, good thermal conductivity and high modules of elasticity. The metallic glassy samples demonstrated good dimensional stability after treatment by the 10 mass% of the triethoxyvinylsilane. Keywords: Polymer-matrix composites, Metallic glass, Adhesion, Mechanical properties, Extrusion

TiO2 nanoparticles (NPs), functionalized poly vinyl chloride (PVC) and polysulfone (PSf) were assembled together in different compositions to fabricate composite membranes with potential application in Cr (VI) and antifouling treatment. Here, TiO2 nanoparticles were synthesized via sol-gel process and Poly vinyl chloride chemically altered with 4-amino benzoic acid. Functionalized PVC was blended uniformly throughout PSf matrix rendering the yellowish-orange color and porous structure giving better productivity. TiO2 NPs were studied for optimum concentration to provide the excess charge for Cr (VI) rejection. SEM images revealed the porous finger like structure within the membranes and the molecular weight cutoff confirmed the ultrafiltration nature of the membranes. Composites showed good wetting behavior with contact angle (between 67 and 76°) and swelling behavior (≈50–79%). Cr (VI) aqueous rejection and the key parameters namely pressure, pH, filler TiO2 concentration and BSA protein were studied in detail. Maximum of 87 ± 5% rejection of Cr (VI) was obtained with productivity of 6.5 L/m2h at 100 kPa pressure in acidic medium. While the antifouling experiments indicated incorporation of TiO2 NPs increased the flux recovery ratio, presence of BSA protein in feed solution showed binding effects with Cr2O72− anions. The membranes showed good reusability for continuous 3 cycles maintaining the rejection efficiency above 70 ± 5% at the end of 3rd cycle.

The potential of filter paper as a substrate material and 4-aminophenyl sulfone (APS) as a novel monomer for TFC fabrication is explored for the first time. A novel polyamide selective layer was developed using APS and trimesoyl chloride by interfacial polymerization, whereas the control TFC was prepared by replacing APS with m-phenylenediamine. Formation of the interfacial selective layer was verified by ATR-IR spectra and the stability of the selective surface coatings was discussed by investigating the monomer interaction. Surprisingly, after polymerization, interconnected, cross-linked structure of two monomers was observed. Desalination studies were carried out in FO mode and PRO mode using NH4HCO3 as a draw solution. Maximum of 90% and 95% rejection was obtained for NaCl and Na2SO4 salts with a flux of 2.51 and 2.17 LMH respectively. The separation efficiency of the prepared TFC membrane was compared against the likes of a commercial TFC membrane under the same conditions.

Thermal sensitive сoiled artificial muscles with a large muscle stroke (87%) based on oriented ultrahigh molecular weight polyethylene fibers were created. The storage modulus and the recovery stress were used as indicators to determine the optimal conditions for the orientation process of the UHMWPE fibers. The working mechanism of the coiled artificial muscles was discussed in terms of a one-way shape memory effect (SME).

Summary Ball milling technique was used for deposition of the polytetrafluoroethylene (PTFE) coating on the powder of TiFe intermetallic compound. Measurement of pressure–composition hydrogen absorption isotherms revealed that the polymer-coated TiFe intermetallic compound kept its hydrogen storage ability. The TiFe/PTFE material demonstrated resistance to surface poisoning even after a prolonged exposure to air and was not subjected to pulverization during multiple hydrogenation–dehydrogenation cycles. Copyright © 2015 John Wiley & Sons, Ltd.

The hydroxyapatite coatings were deposited by mechanical alloying on Ti substrates using vibratory and planetary ball mills. The structure and morphology of the deposited coatings were analyzed by X-ray diffraction and scanning electron microscopy. The tribological properties and biocompatibility of the deposited coatings were also studied. A relatively high density and adhesion coating were observed for the coating obtained in a vibratory ball mill for powder mixture ratio of hydroxyapatite to α-Ti as 1:1, respectively. The average value of the hemolysis of the obtained coating was about 6.98%, which was statistically significant.

In the present work we analyze the structure parameters of the dual-axially forged submicrocrystalline structure Ti88.5Fe5Cu5Al1.5 alloy after forging operation and subsequent annealing. It was shown that the mechanical properties of the dual-axially forged samples depend mostly on the grain size. Formation of the large grains in the structure of the samples, after dual-axial forging operation, causes decrease in the tensile mechanical properties. In order to prevent formation of large grains in the structure, initialization of the process of primary recrystallization is required. In addition to the formation of relatively fine equiaxed grain structure subsequent quenching operation is also useful to hamper crystal growth.

A series of nanostructured alloys based on TiFe intermetallic compound were synthesized from the metallic elements in a planetary ball mill by solid state mechanical alloying. Mg and S were added as doping components to a Fe–50% (at.) Ti powder mixture. Phase and structure transformations during mechanical alloying and subsequent annealing as well as hydrogen interaction with the alloys prepared were studied. It was shown that reversible hydrogen sorption capacities of the nanostructured alloys based on TiFe intermetallic compound were of 0.6 and 0.7 wt.% at room temperature for the alloys with S and Mg, respectively. The alloys studied demonstrated a simplified activation of hydrogenation, especially for the S-containing one.

The structure, magnetostriction and damping properties of Fe82Ga(18–x)Alx (x = 0, 5, 8, 12) alloys were analyzed. The anelastic response of Fe–18(Ga + Al) alloys was studied as a function of temperature (from 0 to 600 °C), frequency (from 0.01 to 200 Hz) and amplitude (from 0.0004% to 0.2%) of forced vibrations. The origin of the relatively high damping capacity of Fe–Ga–Al alloy at room temperature was determined by applying a magnetic field and different heat treatment regimes. The substitution of Ga by Al in Fe–18% Ga alloys was found to decrease magnetostriction and damping. The heat treatment of alloys influences the damping capacity of alloys more than variations of their chemical compositions. Thermally activated frequency and temperature-dependent anelastic effects in Fe–Ga–Al alloys were analyzed and the corresponding activation parameters for relaxation processes were evaluated. Internal friction effects caused by structural transformations were recorded and were found to be consistent with the A2 → D03 → L12 reaction. Thus, the physical mechanisms for all anelastic effects are discussed.

In the present work we introduce a micro/nano-structured α+β Ti-based low-alloy produced by the tilt-casting method and subjected to subsequent thermo-mechanical treatment. After hot dual-axial forging at 900 °C, subsequent heating at 700 °C and water quenching a Ti 94 Fe 3 Cu 3 +1000 ppm of boron alloy, containing inexpensive alloying elements, showed an ultimate tensile strength value of about 950 MPa and percentage elongation of about 5.2%. It is shown that the intensive forging treatment and subsequent heat treatment are leading to significantly improved mechanical properties of such an alloy compared to the as-cast state.

The deformation behavior of bulk metallic glasses and dual-phase crystal/glassy materials was analyzed using the stress–strain diagrams, in-situ video recording and subsequent macro- and micro-structure observation. As a result a two-stage deformation mechanism is observed. The stages are related to the initiation and propagation of multiple shear bands in the beginning of the deformation process as well as the formation and propagation of the dominant shear band at the later stage finally leading to large shear offsets and failure of the sample.

Samples of Zr62.5Cu22.5Fe5Al10 bulk metallic glass are subjected to uniaxial compression. Comparison of tests in monotonic loading and cyclic loading (repeated loading to the onset of plasticity, then unloading) shows that the compressive plasticity of the glass is drastically reduced under cyclic loading. It is argued that this effect arises from stress reversal accelerating the concentration of shear on a dominant shear band. The link with compression–compression fatigue results, and the consequences for low-cycle fatigue of metallic glasses are considered.

A series of nanostructured alloys based on TiFe intermetallic compound were synthesized from the metallic elements in a planetary ball mill by solid state mechanical alloying. Al and Cr were added as doping components to a Fe-50% (at.) Ti powder mixture. Phase and structure transformations during mechanical alloying and subsequent annealing as well as hydrogen interaction with the alloys prepared were studied. It was shown that reversible hydrogen sorption capacity of the nanostructural alloys based on the TiFe intermetallic compound was of 0.7 wt.% at room temperature. The alloys studied demonstrated a simplified activation of hydrogenation. A correlation between the alloys behavior in their reactions with hydrogen and structure parameters of the hydrogenated samples has been discussed.

Dynamic mechanical behavior of the Ni 40 Cu 10 Ti 33 Zr 17 alloy containing high-temperature cubic and glassy phases was studied in pseudo-elastic mode at relatively small deformations. Amplitude dependent internal friction was measured by increasing the maximal strain amplitude e 0 step by step. Two types of tests were applied: a simple test with increase in the amplitude of strain (loading) within each step of loading and a hysteresis loop measurement test. At least three hysteresis loops ‘loading–unloading’ we measured at each step, and the maximal amplitude was increased at each subsequent step. The results indicate that martensitic transformation in this composite alloy starts in a pseudo-elastic deformation mode and contributes to the internal friction observed in the studied alloy.

As-cast Ti-Cu-based alloys containing 1000 mass ppm of boron were investigated in the present work. With respect to a base compositional formula of (Ti-Zr) 49.5+x (Cu-Ni) 49.5− x Fe 1 , we investigated the effect of sample size on the phase constitutions and related mechanical properties of the alloys, with the goal of producing crystal-glassy composites. The effect of Fe addition on the phase constitution of as-cast Ti-Cu-based alloys was also investigated, and the obtained results were compared with those of our previous studies, in which we investigated similar alloys containing no Fe. It was demonstrated that the addition of Fe leads to the formation of a CuTi 2 intermetallic compound, while decreasing the cooling rate (by increasing the diameter of the as-cast billets) makes the formation of the CuTi 2 intermetallic compound more favourable. The best combination of mechanical properties was obtained for the alloys containing no CuTi 2 intermetallic compound.

This work presents a comparative study of different properties variation of Pd 40 Ni 40 Si 5 P 15 bulk metallic glass (BMG), namely: density, hardness, relaxation enthalpy and mechanical properties as a function of the sample thickness. The samples were produced in the form of a long pyramid by conventional Cu-mold casting in an Ar atmosphere. The results illustrate significantly different sensitivity of these properties of the glassy phase to the cooling rate. The difference in crystallization behavior is also discussed.

Intermetallic Ni-Al coatings on the Ni substrate were prepared by the mechanical alloying (MA) method in mechanical activators of vibratory and planetary type. It was found that coatings that were fabricated in a high-energy (planetary) activator in comparison with those fabricated in a low-energy (vibratory) activator are more homogeneous, have higher density, and experience better adhesion to the substrate. It was shown that different intermetallic phases (NiAl, NiAl3, and Ni2Al3) can form directly during the MA treatment in the planetary activator.

(Ti–Zr)–(Cu–Ni–Co) bulk metallic alloys were investigated in the present work. Taking compositional formula (Ti–Zr) 49.5+ x (Cu–Ni) 49.5– x Co 1 as a basis, we increased the content of Ti and Zr elements and decreased the content of Cu and Ni with the purpose of production of crystal-glassy composites. Such a kind of approach may allow combination of high strength of glassy alloys and good plasticity of crystalline alloys in these composite materials. According to this approach a large number of the alloys of different composition were prepared and investigated. Ti 43.2 Zr 7.8 Cu 40.8 Ni 7.2 Co 1 bulk glassy-crystal composite sample showed the compressive strength of 1800 MPa and plasticity of about 5%. The effect of Y addition on the glass-forming ability and mechanical properties of the studied alloys was also investigated.

(Ti–Zr)–(Cu–Ni–Co) bulk metallic alloys containing 1000 mass ppm of boron were investigated in the present work. Taking compositional formula (Ti–Zr) 49.5+ x (Cu–Ni) 49.5− x Co 1 as a basis, we increased the content of Ti and Zr elements and decreased the content of Cu and Ni with the purpose of production of crystal–glassy composites. Such a kind of approach may allow combination of high strength of glassy alloys and good plasticity of crystalline alloys in these composite materials. According to this approach a large number of the alloys of different composition and different diameters were prepared and investigated. Some of the prepared bulk glassy-crystal composite samples showes rather good properties: the compressive strength of 1800–2500 MPa and compressive plasticity up to 13.5%.

Ti-based alloys containing Ag were produced by tilt-casting method and their properties were studied. Even in its as-cast state, Ti94Ag3Pd3 showed relatively high tensile properties, good electrochemical behavior and good biocompatibility. The relatively good mechanical properties of the as-cast α-Ti-type Ti94Ag3Pd3 alloy (tensile strength up to 850 MPa and elongation of ~10%) can be explained by its severely deformed, fine crystalline structure. The high biocompatibility of Ti94Ag3Pd3 can be explained by the Ag–Pd interaction, which inhibits the release of Ag ions from the surface. Ag, in combination with Pd has no toxic effects and demonstrates useful antimicrobial properties. The Ti94Ag3Pd3 alloy shows a good potential to be applied as a biomedical implant alloy.

In the present work we introduce a nanostructured low-alloy-type α + β Ti-based alloy produced by tilt-casting method and subjected to subsequent thermo-mechanical treatment. It demonstrates good mechanical properties corresponding to high-alloy-type Ti-based alloys. After hot dual-axial forging at 900 °C Ti94Fe3Cu3 alloy, containing inexpensive alloying elements, showed a high ultimate tensile strength value of 1200 MPa and percentage elongation of 9%. It is shown that the intensive forging treatment is equivalent to severe plastic deformation and provides a nanostructured state (≈50–100 nm crystal size) of the alloy leading to significantly improved mechanical properties even in low-alloys.

The present work represents phase transformations observed upon cyclic loading of Zr62.5Fe5Cu22.5Al10 bulk metallic glassy samples within reversible deformation regime prior to plastic deformation. The structure of the samples was studied by X-ray diffraction and transmission electron microscopy including high-resolution imaging and analysis of selected-area electron diffraction and nanobeam diffraction patterns. Thermal properties of the samples were characterized by differential scanning calorimetry. It is found that kinetically frozen anelastic deformation accumulates at room temperature and causes crystallization of metallic glassy phase forming precursors of metastable crystalline FCC Zr-based phase stabilized by the alloying elements.

The equiatomic intermetallic compound TiFe has been prepared by elemental mechanochemical synthesis in a planetary ball mill from Fe and Ti powders. The structural and phase transformations during synthesis were followed using X-ray diffraction. The reaction of the synthesized compound with hydrogen was studied volumetrically. The results demonstrate that the hydrogen capacity of the mechanochemical TiFe is 1.2 wt % at 2.5 MPa. Its absorption isotherm has an extended plateau in the range 1.6–1.7 MPa at room temperature.

A technique for producing the intermetallic compound FeTi by treatment of Ti-50 at % Fe powder mixtures in a high-energy ball planetary mill in argon atmosphere is demonstrated. The forming compound is in the nanocrystalline state with the size of coherent scattering areas (CSA) of 10–20 nm. A method of sample compaction from powder obtained by mechanical and chemical synthesis is proposed. It combines mechanical strength with initial phase composition and material microstructure. It is determined that, after high-temperature activation, the synthesized compound FeTi reversibly absorbs up to 0.6 wt % of hydrogen at room temperature.